Optimization of air recirculation systems in trona mines

Controlled air recirculation is a local ventilation method used in mines to increase the airflow in the working area and reduce the ventilation cost. This study provides a tool for the design of controlled recirculation systems in order to control dust level in the recirculated air.; For the understanding of the dust particle transportation and deposition in the mine airways, 10 in-mine experimental tests were performed. The results of the experiments were used for a comparative analysis with the predictions of the mathematical models developed for this study. Two water spray systems were designed and tested in the mine returns to measure the collection efficiencies of the systems.; The mathematical models developed include the regression equation of the turbulent deposition velocity in mine airway, the dust flow simulation model to predict the size-dependent dust concentration and the amount of dust deposited along the length of multiple mine airways, and the models for the computation of the quantity and quality of the recirculated air and the air leakage in a recirculation zone. The models were used to perform several sensitivity analyses of the recirculation systems for a trona mine, and model predictions were compared with the actual data.; The study shows that the return entry can be used to clear the dusty air up to a certain level. The particle deposition velocity in a turbulent flow is a function of the distance from the source. The reduction in dust concentration decreased with the increase in the distance from the source, resulting in a fairly uniform dust level away from the working face. The models prediction are in good agreement with the experimental data on the dust concentration and airflow in the conventional ventilation and recirculation systems.